Thread: GFI testing

I searched the achieves, but couldn't find an answer on this, so I wanted to see what the experts recommend.

I recently performed an inspection, where two exterior (1st floor) receptacles didn't trip when tested with my handy GFI tester (standard, 3 prong, with a button). The tester DID trip several other outlets, but didn't trip two outlets. I called out the issue to be reviewed and corrected by an electrician. (The lights on the tester says the receptacles are properly wired - two yellow lights)

This week, the Seller calls me, and says when he trips the GFI in the sub panel (for the exterior) the outlets have no power.

So, A) I am stopping by there tomorrow to check it out, but B) I was wondering if there could be a way the outlets are improperly wired that would prevent them from tripping with the tester, but allow them to be tripped from the GFI breaker...and C) - if that is the case, is that acceptable?

Thanks in advance - best to all and a Merry and Safe Christmas season! - JD JOHNSON

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Yes, it is possible that they might not trip. The test button on the device (outlet or breaker) is the best way to test a GFCI circuit.

Nite-light testers (3-light testers) can't handle more than one problem on a circuit. So if it has RP and another condition it could show that everything is OK.

You need to be sure that the owner is pushing the test button and not just flipping the handle on the breaker and making it turn off.

I have had several occasions where the test button on a GFCI outlet would shut off the power to a circuit of outlets but the test button on my three-prong would not trip the circuit. Improper wiring or bad GFCI. Would still recommend that a qualified electrical contractor investigate.

John, I find that scenario on some GFCI outlets, but I don't report it as a problem. As Scott said, if the Test button on the GFCI outlet trips the outlet, it's working OK.

How many GFCI protection devices are there on that circuit? Three? (Two GFCI outlets and a GFCI breaker?) Why would you need more than one?

Originally Posted by JD Johnson

B) I was wondering if there could be a way the outlets are improperly wired that would prevent them from tripping with the tester, but allow them to be tripped from the GFI breaker...

Two things come to mind, in reverse order:

Cheap tester not 'always' working properly.

Receptacles not grounded (or a false or bootleg ground).

If the 'Test' button on the GFCI works, then it (the GFCI protection) is okay, however, that does not mean that 'all is well' (see above two items).

After going back and forth several times I've finally sworn off the testers with the button.... There are several reasons for this... one is the exact case the OP describes. The 'test' button on the receptacle or the breaker is the best way to test.

Also, I've spent more time than I'd care to admit searching the property for the GFI that tripped when I hit the button to test the outlet in a 'should be GFI protected' area. Unfortunately, we're at the mercy of the way an electrician or some goofball homeowner wired things. As murphy likes it, the reset button will be behind the moving boxes and three refigerators full of New York steaks.

I carry a three prong tester that I use 90% of the time.... I also carry a basic two prong 'wiggy' tester to zero in on the wiring once I get a problem with the three prong.... or of course for the two prong outlets. I also use a pen type voltage sniffer to easily ID live cables and to save my butt while in crawl spaces and attics with a bunch of potentially live stuff. I've heard people passionantly endorse one of these tester as the 'best' to use.... I couldn't imagine not having all three.

The manufacturer's of GFCI devices recognize only their button on the device itself and not a pocket tester since the two most likely will not have the same calibration/sensitivity.

And I agree completely with Matt, wiggy is far more reliable than the three prong tester. I most likely use the three prong too much and chances are quite good that I've missed some problems by not using the wiggy instead. I think that you could say that there's a lazy factor in there somewhere.

Thank you for your insight, and answers. As it turns out - the Seller was wrong, and we were correct in accuratly identifying a hazardous defecency. But I know have a better understanding about GFI wiring!

Merry Merry to all! - JDJ

I don't know about you guys, but I've had several GFCI receptacles thru the years where the "reset" button pops out when pressing the "test" button on the receptacle. You would think that it was functioning properly, but my 3 light tester shows that power IS NOT killed to the receptacle. That's why I use a 3-light tester and the button on the receptacle itself.

Originally Posted by Kevin Barre

... thru the years ... You would think that it was functioning properly, but my 3 light tester shows that power IS NOT killed to the receptacle. That's why I use a 3-light tester and the button on the receptacle itself.

Those are wired with line/load reversed.

No need to use the 3 light tester *for testing the GFCI function* - which is what was being discussed.

You are using the 3 light tester simply to verify that the GFCI is no longer hot. That should be a standard check made when any GFCI receptacle device is tripped with its test button. The newer ones will not reset if they are wired reversed, so they would not work to start with. The older ones will reset regardless. But you don't need your 3 light tester, you could use a tic tracer for that, or any tester.

Originally Posted by Jerry Peck

Those are wired with line/load reversed.

No need to use the 3 light tester *for testing the GFCI function* - which is what was being discussed.

You are using the 3 light tester simply to verify that the GFCI is no longer hot. That should be a standard check made when any GFCI receptacle device is tripped with its test button. The newer ones will not reset if they are wired reversed, so they would not work to start with. The older ones will reset regardless. But you don't need your 3 light tester, you could use a tic tracer for that, or any tester.

I assumed everyone understood that my use of the 3 light tester is simply to verify that there is no power still available at the receptacle. For those who have never experienced it, I was merely pointing out that the fact that the reset button pops out is not a guarantee that the receptacle is killing power. The 3 light tester is a lot smaller (and faster to use) than anything else I can carry around to plug in to verify that the receptacle is not still hot.

Kevin,

Great point. I think that this is one example where we need to expand our comment from GFCI not functioning to something along the line of power does not trip when GFCI is tested. Otherwise someone will come along, push the test button and hear it pop out and figure there is no problem.

My standard comment is that "the gfi failed to lose power when the 'test' button was triggered indicating that it's wired incorrectly or malfunctioning. This should be repaired or replaced to function properly." I know most, if not all, of the time it's wired wrong.

As for testing during the course of the inspection, I test the GFI and leave my tester in the outlet then use my voltage sniffer to tell exactly where power was cut.

Originally Posted by Eric Barker

Otherwise someone will come along, push the test button and hear it pop out and figure there is no problem.

That's what I was trying to get across in my (apparently) less than effective way initially.

We must test all outlets where a GFCI is required.

Many three prong outlets are wired to GFCI's outlets in the same circuit for protection.

These outlets need to be tested with a three prong GFCI tester (or other) to determine if they have ground fault protection. I know of no other "logical" way to do it. (note the word logical)

I know they should be labeled "GFCI protected", but that's another issue.